The human body contains around 60% water.
A study recommended that you drink eight 8-ounce (237-mL) water per day (the 8×8 rule).
Although there is little science behind this particular rule, staying hydrated is very important.
If you do not stay hydrated, your physical performance can disturb. Drinking enough water is particularly important during intense exercise or high heat.
Dehydration can easily be visible if you miss as little as 2% of your body’s water content. However, it is not unusual for athletes to lose as much as 6–10% of their water weight via sweat. It can lead to altered body temperature control, reduced motivation, and increased fatigue. It can also make exercise feel much more challenging, both physically and mentally.